PHILIPS 14TX3004/08S CHASSIS TX3 INTERNAL VIEW.

ON and OFF switch is integrated on the volume regulator.

PHILIPS  14TX3004/08S  CHASSIS  TX3 MAIN COMPONENT BASE:


TDA3190 TV SOUND CHANNEL (sgs)

The TDA3190 is a monolithic integrated circuit in a
16-lead dual in-line plastic package. It performs all
the functions needed for the TV sound channel :

.IF LIMITER AMPLIFIER .ACTIVE LOW-PASS FILTER
.FM DETECTOR
.DC VOLUMECONTROL
.AF PREAMPLIFIER .AF OUTPUT STAGE

DESCRIPTION
The TDA3190 can give an output power of 4.2 W
(d = 10 %) into a 16 W load at VS = 24 V, or 1.5 W
(d = 10 %) into an 8 W load at VS = 12 V. This
performance, togetherwith the FM-IF section characteristics
of high sensitivity, highAM rejection and
low distortion, enables the device to be used in
almost every type of television receivers.
The device has no irradiation problems, hence no
external screening is needed.
The TDA3190 is a pin to pin replacement of
TDA1190Z.

The electrical characteristics of the TDA3190 remain
almost constant over the frequencyrange 4.5
to 6 MHz, therefore it can be used in all television
standards (FM mod.). The TDA3190 has a high
input impedance,so it can work with a ceramic filter
or with a tuned circuit that provide the necessary
input selectivity.
The value of the resistors connected to pin 9,
determine the AC gain of the audio frequency amplifier.
This enables the desired gain to be selected
in relation to the frequency deviation at which the
output stage of the AF amplifier, must enter into
clipping.
Capacitor C8, connected between pins 10 and 11,
determines the upper cutoff frequency of the audio
bandwidth.To increase the bandwidth
the values of C8 and C7 must be reduced, keeping the ratio
C7/C8 as shown in the table of fig. 16.
The capacitor connected between pin 16 and
ground, together with the internal resistor of 10 KW
forms the de-emphasis network. The Boucherot
cell eliminates the high frequency oscillations
caused by the inductiveload and thewires connecting
the loudspeaker.


TDA2548 VIF IF VIDEO (PHILIPS)


Power supply is realized with mains transformer and Linear transistorized power supply stabilizer, A DC power supply apparatus includes a rectifier circuit which rectifies an input commercial AC voltage. The rectifier output voltage is smoothed in a smoothing capacitor. Voltage stabilization is provided in the stabilizing circuits by the use of Zener diode circuits to provide biasing to control the collector-emitter paths of respective transistors.A linear regulator circuit according to an embodiment of the present invention has an input node receiving an unregulated voltage and an output node providing a regulated voltage. The linear regulator circuit includes a voltage regulator, a bias circuit, and a current control device.

In one embodiment, the current control device is implemented as an NPN bipolar junction transistor (BJT) having a collector electrode forming the input node of the linear regulator circuit, an emitter electrode coupled to the input of the voltage regulator, and a base electrode coupled to the second terminal of the bias circuit. A first capacitor may be coupled between the input and reference terminals of the voltage regulator and a second capacitor may be coupled between the output and reference terminals of the voltage regulator. The voltage regulator may be implemented as known to those skilled in the art, such as an LDO or non-LDO 3-terminal regulator or the like.
The bias circuit may include a bias device and a current source. The bias device has a first terminal coupled to the output terminal of the voltage regulator and a second terminal coupled to the control electrode of the current control device. The current source has an input coupled to the first current electrode of the current control device and an output coupled to the second terminal of the bias device. A capacitor may be coupled between the first and second terminals of the bias device.
In the bias device and current source embodiment, the bias device may be implemented as a Zener diode, one or more diodes coupled in series, at least one light emitting diode, or any other bias device which develops sufficient voltage while receiving current from the current source. The current source may be implemented with a PNP BJT having its collector electrode coupled to the second terminal of the bias device, at least one first resistor having a first end coupled to the emitter electrode of the PNP BJT and a second end, a Zener diode and a second resistor. The Zener diode has an anode coupled to the base electrode of the PNP BJT and a cathode coupled to the second end of the first resistor. The second resistor has a first end coupled to the anode of the Zener diode and a second end coupled to the reference terminal of the voltage regulator. A second Zener diode may be included having an anode coupled to the cathode of the first Zener diode and a cathode coupled to the first current electrode of the current control device.
A circuit is disclosed for improving operation of a linear regulator, having an input terminal, an output terminal, and a reference terminal. The circuit includes an input node, a transistor, a bias circuit, and first and second capacitors. The transistor has a first current electrode coupled to the input node, a second current electrode for coupling to the input terminal of the linear regulator, and a control electrode. The bias circuit has a first terminal for coupling to the output terminal of the linear regulator and a second terminal coupled to the control electrode of the transistor. The first capacitor is for coupling between the input and reference terminals of the linear regulator, and the second capacitor is for coupling between the output and reference terminals of the linear regulator. The bias circuit develops a voltage sufficient to drive the control terminal of the transistor and to operate the linear regulator. The bias circuit may be a battery, a bias device and a current source, a floating power supply, a charge pump, or any combination thereof. The transistor may be implemented as a BJT or FET or any other suitable current controlled device.